The following discussion of the background of the disclosure is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge as of the priority date of any of the claims.
Laryngeal masks are used in connection with the establishment of passage of air to the respiratory tracts, while simultaneously blocking the respiratory air passage to the oesophagus. The laryngeal mask is shaped such that it has a lumen within a mask portion arranged at the distal end of an airway tube, i.e. the end of the airway tube facing towards the laryngeal opening, when the laryngeal mask is correctly placed in a patient and the cuff inflated. Around that lumen a generally elliptical, inflatable, peripheral cuff is provided, so as to form a seal around the laryngeal opening when the laryngeal mask is correctly placed in a patient and the cuff inflated. In order to be able to inflate the cuff, an inflation tube is connected to an inflation means, such as a balloon and a valve outside the patient. Operating the inflation means allows the peripheral cuff of the laryngeal mask to be inflated thereby ensuring a tight abutment of the laryngeal mask. Using the valve, the peripheral cuff may be deflated when the laryngeal mask is no longer needed and has to be removed from the patient.
Optionally, the laryngeal mask may be fitted with a passage for allowing access to the oesophagus through the mask. The passage may be utilized to evacuate or drain gastric content, to insert an instrument, or for other purposes.
Laryngeal masks generally exhibit mirror symmetry. The gastric tube may extend in the central anterior/posterior plane along the back of the airway tube all the way to the back of the inflatable cuff. The gastric tube may also be bifurcated, extending along either side of the airway tube in mirror image symmetry, and joining in the central plane just before the gastric tube passes through the cuff.
Though this mirror symmetry is largely desired to match the human body, mirror symmetry presents manufacturing drawbacks. Additionally, it is desirable to cost-effectively manufacture laryngeal masks that will remain in place even as the patient's head or the patient are moved, without unduly stressing the patient.